Elastomeric materials

ABSTRACT

Some embodiments of the present invention include elastomeric films with a basis weight of about 40 gsm or less or about 25 gsm or less. Other embodiments include elastomeric laminates comprising the elastomeric film bonded to one or more substrates (such as nonwoven fabrics). Methods of making the elastomeric films and elastomeric laminates are also provided.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of co-pending U.S. patent applicationSer. No. 12/358,533 filed Jan. 23, 2009, which claims the benefit ofU.S. Provisional Application No. 61/023,107, filed Jan. 24, 2008, bothof which are herein incorporated by reference in their entirety.

BACKGROUND

Elastomeric materials have the ability to expand to fit over or aroundan object, and then retract to provide a snug fit around the object.Elastomeric materials can be used in garments to provide a snug fit,such as in active wear. Elastomeric materials can also form resilientand effective barriers, such as in the cuffs of thermal garmentsintended to retain body heat.

One example of a type of garment where both fit and barrier propertiesare important is personal hygienic products such as diapers. Elastomericmaterials can be used in the waist, around the leg openings, and in thefasteners (for a diaper) or sides (for an underpants-type garment). Theelastomeric materials in these regions can improve the overall fit ofthe garment, and also make it much easier to both don and remove thegarment. The elastomeric materials also act as resilient barriers,improving the containment capabilities of the garment while stillallowing comfort and free movement to the wearer.

Elastomeric materials can be expensive and producing thin films ofexpensive material can therefore reduce cost. However, producing thinfilms can be complicated due to tearing and pinholing.

There remains a need for an inexpensive elastomeric film, or aninexpensive laminate of an elastomeric film that is bonded to one ormore layers of substrate, such as fabric. There also remains a need foran elastomeric film or laminate that has good elastomeric properties,such as permanent set. Such a film or laminate can be suitable forimproving the fit and comfort of garments and personal care items,including limited-use and disposable items.

SUMMARY

Some embodiments of the present invention relate to an elastomeric filmcomprising a layer comprising (i) at least one olefin-based elastomericpolymer, and (ii) at least one draw down polymer. The elastomeric filmhas a basis weight of no more than about 25 gsm and has a permanent setof no more than about 15% after recovery from being stretched to 100% ofits original size.

Other embodiments include a multilayer elastomeric film with two or morelayers comprising (1) a first layer comprising (a) at least oneolefin-based elastomeric polymer and (b) at least one first draw downpolymer, and (2) a second layer comprising (a) at least one elastomericpolymer and (b) at least one second draw down polymer. The multilayerelastomeric film has a basis weight of no more than about 40 gsm and hasa permanent set of no more than about 15% after recovery from beingstretched to 100% of its original size. And at least one elastomericpolymer of the second layer can be an olefin-based elastomeric polymer,a non-olefin-based elastomeric polymer, or combinations thereof.

Other embodiments include a multilayer elastomeric film that furthercomprises a third layer comprising at least one second elastomericpolymer and at least one third draw down polymer.

Some embodiments of the invention include a laminate comprising a filmthat can be a monolayer elastomeric film or a multilayer elastomericfilm and at least one substrate. The film and the substrate arelaminated together to form the laminate. Further embodiments include amethod for making an elastomeric film comprising extruding a mixtureinto a layer of a film. The mixture comprises at least one olefin-basedelastomeric polymer and at least one draw down polymer.

Some embodiments include a method for making a multilayer elastomericfilm with at least two layers comprising coextruding a first layer and asecond layer. The first layer comprises at least one olefin-basedelastomeric polymer and at least one first draw down polymer. The secondlayer comprises at least one elastomeric polymer and at least one seconddraw down polymer.

Other embodiments include a method for making a multilayer elastomericfilm with at least three layers comprising coextruding a first layer, asecond layer, and a third layer. The first layer comprises at least oneolefin-based elastomeric polymer and at least one first draw downpolymer. The second layer comprises at least one elastomeric polymer andat least one second draw down polymer. The third layer comprises atleast one second elastomeric polymer and at least one third draw downpolymer.

Some embodiments include a method for making a laminate comprisinglaminating a film to at least one substrate. The film is an elastomericfilm or a multilayer elastomeric film.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood in view of the drawings, inwhich:

FIG. 1 is a schematic of a typical cast coextrusion process;

FIG. 2 is a schematic of a typical adhesive lamination process; and

FIG. 3 is a schematic of a typical extrusion coating process.

DETAILED DESCRIPTION

For the purpose of this disclosure, the following terms are defined:

-   -   “Film” refers to material in a sheet-like form where the        dimensions of the material in the x (length) and y (width)        directions are substantially larger than the dimension in the z        (thickness) direction.    -   “Basis weight” is an industry standard term that quantifies the        thickness or unit mass of a film or laminate product. The basis        weight is the mass per planar area of the sheet-like material.        Basis weight is commonly stated in units of grams per square        meter (gsm) or ounces per square yard (osy).    -   “Coextrusion” refers to a process of making multilayer polymer        films. When a multilayer polymer film is made by a coextrusion        process, each polymer or polymer blend comprising a layer of the        film is melted by itself. The molten polymers may be layered        inside the extrusion die, and the layers of molten polymer films        are extruded from the die essentially simultaneously. In        coextruded polymer films, the individual layers of the film are        bonded together but remain essentially unmixed and distinct as        layers within the film. This is contrasted with blended        multicomponent films, where the polymer components are mixed to        make an essentially homogeneous blend or heterogeneous mixture        of polymers that are extruded in a single layer.    -   “Laminate” as a noun refers to a layered structure of sheet-like        materials stacked and bonded so that the layers are        substantially coextensive across the width of the narrowest        sheet of material. The layers may comprise films, fabrics, other        materials in sheet form, or combinations thereof. For instance,        a laminate may be a structure comprising a layer of film and a        layer of fabric bonded together across their width such that the        two layers remain bonded as a single sheet under normal use. A        laminate may also be called a composite or a coated material.        “Laminate” as a verb refers to the process by which such a        layered structure is formed.    -   “Extrusion lamination” or “extrusion coating” refer to processes        by which a film of molten polymer is extruded onto a solid        substrate, in order to coat the substrate with the molten        polymer film to bond the substrate and film together.    -   “Elastomeric” or “elastomer” refer to polymer materials which        can be stretched to at least about 150% or more of their        original dimension, and which then recover to no more than about        120% of their original dimension in the direction of the applied        stretching force. For example, an elastomeric film that is 10 cm        long should stretch to at least about 15 cm under a suitable        stretching force, and then retract to no more than about 12 cm        when the stretching force is removed. Elastomeric materials are        both stretchable and recoverable.    -   “Permanent set” is the permanent deformation of a material after        removal of an applied load. In the case of elastomeric films,        permanent set is the increase in length of a sample of a film        after the film has been stretched to a given length and then        allowed to relax. Permanent set is typically expressed as a        percent increase relative to the original size. For example, if        a 10 cm piece of elastomeric film is stretched to 20 cm, then        allowed to relax, and the resulting relaxed film is 11.5 cm in        length, the permanent set of the film is 15%.

The test method used to measure permanent set is based upon ASTM D882-97with the following details. The sample is cut to make one inch by sixinch specimens—the six inch length is in the direction the of the filmor laminate is being tested (e.g., in the CD direction for the examplesbelow). An MTS Tensile Tester (Qtest) is used to measure the sampledeformation. The tester grip faces are rubber grip faces that are 25 mmwide (MTS part No. 56163829). The sample is loaded with a grip distanceset at two inches from the center of upper grip face to the center ofthe lower grip face. The strain endpoint is set to 100%. The firstupload cycle is run at a rate of 20 inches/minute to the strainendpoint, then immediately returns to 0% strain at a rate of 20inches/minute, and then is held at 0% strain for 30 seconds. The secondupload cycle is run at a rate of 20 inches/minute to the strainendpoint, and then immediately returns to 0% strain at a rate of 20inches/minute. The permanent set is calculated at the point when loadreaches eight grams of force during the second upload cycle.

-   -   “Stretchable” and “recoverable” are descriptive terms used to        describe the elastomeric properties of a material. “Stretchable”        means that the material can be extended by a pulling force to a        specified dimension significantly greater than its initial        dimension without breaking. For example, a material that is 10        cm long that can be extended to about 13 cm long without        breaking under a pulling force could be described as        stretchable. “Recoverable” means that a material which is        extended by a pulling force to a certain dimension significantly        greater than its initial dimension without breaking will return        to its initial dimension or a specified dimension that is        adequately close to the initial dimension when the pulling force        is released. For example, a material that is 10 cm long that can        be extended to about 13 cm long without breaking under a pulling        force, and which returns to about 10 cm long or to a specified        length that is adequately close to 10 cm could be described as        recoverable.    -   “Extensible” refers to polymer materials that can be stretched        at least about 130% of their original dimension without        breaking, but which either do not recover significantly or        recover to greater than about 120% of their original dimension        and therefore are not elastomeric as defined above. For example,        an extensible film that is 10 cm long should stretch to at least        about 13 cm under a stretching force, then either remain about        13 cm long or recover to a length more than about 12 cm when the        stretching force is removed. Extensible materials are        stretchable, but not recoverable.    -   “Activation” or “activating” refers to a process by which the        elastomeric film or material is rendered easy to stretch. Most        often, activation is a physical treatment, modification or        deformation of the elastomeric film. Stretching a film for the        first time is one means of activating the film. An elastomeric        material that has undergone activation is called “activated.” A        common example of activation is blowing up a balloon. The first        time the balloon is inflated (or “activated”), the material in        the balloon is stretched. If the inflated balloon is allowed to        deflate and then blown up again, the “activated” balloon is much        easier to inflate.    -   “Film strength” or “mechanical strength” are the tensile        properties of a film or laminate, as measured by ASTM D-822        “Tensile Properties of Thin Plastic Sheeting.” Unless noted        otherwise, “film strength” or “mechanical strength” refers        specifically to tensile at break and % elongation at break.    -   “Tear strength” is a property of a film which determines the        ease or difficulty by which the film can be torn starting from a        notch or aperture cut into the film, as measured by the notched        Elmendorf test, ASTM D-1922.    -   “Bond strength” is a property of a laminate comprising two or        more layers. The bond strength is determined by measuring the        force required to peel apart the laminate layers after they are        bonded together. Bond strength can be measured by methods such        as ASTM D-1876 or ASTM F-904.    -   “Pinholing” refers to the formation of small holes or tears in a        film while the film is being formed, laminated, activated, or        other manufacturing or processing step. “Pinholes” are the small        holes or tears so formed. Pinholes are typically in the range of        about 100 μm to 1 cm in size.    -   “Processability” is a catch-all term to qualitatively describe        the ease with which a composition comprising a polymer resin or        polymer resin blend can be extruded to form a film. If a polymer        composition has good processability, it can be easily extruded        into a uniform film with a smooth surface, controlled and        uniform thickness, thinner gauge, homogeneous composition, etc.        Poor processability is demonstrated by problems such as draw        resonance, ‘shark skin’ surfaces, poor thickness control,        inability to reduce the film gauge, etc.    -   “Blocking” refers to the phenomenon of a material sticking to        itself while rolled, folded, or otherwise placed in intimate        surface-to-surface contact, due to the inherent stickiness or        tackiness of one or more of the material components. Blocking        can be quantified by ASTM D3354 “Blocking Load of Plastic Film        by the Parallel Plate Method.”    -   “Robust” refers generally to the tendency of a film, laminate,        or other sheet-like material to remain intact and resist        tearing, shredding, pinholing, or other forms of material        failure while under applied stress or other physical        manipulation. For example, a film which resists tearing under a        given stress is described as ‘more robust’ than another film        which tears under equivalent stress.

According to the present invention, as discussed herein, an elastomericfilm with a low basis weight can be produced. In some embodiments, theelastomeric film is a monolayer film of a polyolefin-based layer. Theelastomeric film can also be a multilayer film having a polyolefin-basedlayer. The multilayer film can have a total of, for example, two layers,three layers, four layers, five layers, six layers, seven layers, oreight or more layers. The elastomeric film can also be part of alaminate formed with one or more substrates, such as nonwoven fabrics.

The monolayer elastomeric film comprises a polyolefin-based layer thatcomprises one or more olefin-based elastomeric polymers blended with oneor more draw down polymers.

The draw down polymer is a polymer that adds or enhances one or morefilm properties or processing properties, such as those that aid inprocessability during film preparation. For example, the draw downpolymer can aid in the production of reduced-gauge (i.e., thin) films.In some embodiments, the draw down polymer can aid in the filmextrusion, such as by helping to provide an increased line speed orreduce draw resonance. Other possible processability benefits from theaddition of the draw down polymer include improving the melt curtainstability, providing a smooth film surface, providing a lower viscosityof the polymer melt, providing better resistance to heat (e.g.,increasing the film's heat capacity or thermal stability), providingresistance to tearing, providing resistance to pinhole formation,providing a controlled and uniform thickness, or providing a homogeneouscomposition. The draw down polymer can act as a processing aid thatlubricates the die to reduce sticking (e.g., of elastomeric polymers)and flow resistance of the molten elastomeric resin. Of course, theaddition of the draw down polymer can provide one or a combination ofthese aids to film extrusion or processability.

There are many examples of draw down polymers. For example, a linearlow-density polyethylene (e.g., ELITE™ 5800 provided by Dow ChemicalCorp. of Midland, Mich.) can be added to a layer of the film compositionto lower the viscosity of the polymer melt and enhance theprocessability of the extruded film. High-impact polystyrene (HIPS)(e.g., STYRON™ 485 from Dow Chemical Corp. of Midland, Mich.; IneosNova473D from IneosNova of Channahon, Ill.) can help control the filmmodulus, improve the toughness of the film, and reduce the overall costof the elastomeric material. Polypropylene can improve the robustness ofthe elastomer and improve the films' resistance to pinholing andtearing. Homopolymer polypropylene (hPP) (e.g., INSPIRE™ D118 from DowChemical Corp. of Midland, Mich.; Polypropylene 3622 from TotalPetrochemicals of Houston, Tex.) can be added to improve processability.hPP is a form of polypropylene which is highly crystalline andcontaining essentially 100% propylene monomer. In some embodiments, hPPis added to a layer comprising an elastomeric polymer (e.g., styreneblock copolymers), as discussed below; the addition can result, in someinstances, in a film that can be extruded at a thinner gauge, withimproved gauge uniformity, or with reduced tendency to experience drawresonance during extrusion.

The draw down polymers can be linear low density polyethylene,propylene, homopolymer polypropylene, high impact polystyrene, andmixtures thereof. The draw down polymer can be a polymer which has beenprepared using a single-site catalyst such as a metallocene catalyst andcan be, for example, a polyolefin produced using a metallocene catalyst(e.g., ELITE™ 5800 provided by Dow Chemical Corp. of Midland, Mich.).The identity and amount of draw down polymer can depend on the othercomponents in the layer (e.g., the identity of the olefin-basedelastomeric polymer(s) in the layer), other components of the film or,if applicable, components of the laminate that comprises the film. Thetotal amount of draw down polymer can be present in an amount effectiveto enhance one or more film properties that aid in processability duringfilm preparation; for example, the total amount of draw down polymer canbe present in an amount effective to provide a film gauge of about 25gsm, about 20 gsm, about 15 gsm, or about 10 gsm. The total amount ofdraw down polymer (i.e., the combined amount of the one or more drawdown polymer(s)) can be about 5%, about 10 wt %, about 15 wt %, about 20wt %, about 25 wt %, about 30 wt %, about 35 wt %, about 40 wt %, orabout 45 wt %. The wt % is relative to the layer weight (i.e., totalweight of draw down polymer(s) divided by the total weight of thelayer). In some instances the total amount of the draw down polymer isat least about 5 wt %, at least about 10 wt %, or at least about 15 wt%. The total amount of draw down polymer can be no more than about 20 wt%, no more than about 25 wt %, no more than about 30 wt %, no more thanabout 35 wt %, or no more than about 45 wt %.

The olefin-based elastomeric polymer can be olefin block copolymer,olefin random copolymer, ethylene copolymer, propylene copolymer, ormixtures thereof. In some embodiments, the olefin-based elastomericpolymer is not a block copolymer of vinyl arylene and conjugated diene,natural rubber, polyurethane rubber, polyester rubber, elastomericpolyamide, elastomeric polyether, polyisoprene, polyneoprene, ormixtures thereof. In some embodiments, olefin-based elastomeric polymercan be ethylene olefin block copolymer, propylene olefin blockcopolymer, ethylene olefin random copolymer, propylene olefin randomcopolymer, or mixtures thereof. In other embodiments, the olefin-basedelastomeric polymer can be ethylene-propylene random copolymer,ethylene-butene random copolymer, ethylene-pentene olefin blockcopolymer, ethylene-hexene random copolymer, ethylene-heptene olefinblock copolymer, ethylene-octene olefin block copolymer, ethylene-noneneolefin block copolymer, ethylene-decene olefin block copolymer,propylene-ethylene olefin block copolymer, ethylene α-olefin copolymer,ethylene α-olefin random copolymer, ethylene α-olefin block copolymer,or mixtures thereof. Examples of olefin-based elastomeric polymers areolefin block copolymers (OBCs) which are elastomeric copolymers ofpolyethylene, sold under the trade name INFUSE™ by The Dow ChemicalCompany of Midland, Mich. (e.g., INFUSE™ 9107). Other examples ofolefin-based elastomeric polymers are copolymers of polypropylene andpolyethylene, sold under the trade name VISTAMAXX™ by ExxonMobilChemical Company of Houston, Tex. (e.g., VISTAMAXX™ 6102). The totalamount of the olefin-based elastomeric polymer(s) can be, relative tothe layer weight, about 10 wt %, about 20 wt %, about 30 wt %, about 40wt %, about 50 wt %, about 60 wt %, about 70 wt %, about 80 wt %, orabout 90 wt %. In some instances, total amount of the olefin-basedelastomeric polymer(s) can be at least about 10 wt %, at least about 20wt %, at least about 50 wt %, or at least about 70 wt %. The totalamount of the olefin-based elastomeric polymer(s) can be no more thanabout 70 wt %, no more than about 80 wt %, or no more than about 90 wt%.

The olefin-based elastomeric polymer can be present in an amount toprovide or enhance properties (including processing properties) of theolefin-based layer or of the elastomeric film. The olefin-basedelastomeric polymer can provide better resistance to heat (e.g.,increasing the film's heat capacity or thermal stability), compared to,for example, unsaturated styrene block copolymer elastomers. This betterresistance to heat can aid in processing or extrusion; for example, afilm comprising olefin-based elastomeric polymers can make it possibleto extrude at higher temperatures without significant thermaldegradation, at lower viscosity, at a thinner gauge without tearing orpinholing, or combinations thereof. Olefin-based elastomeric polymerscan have other enhanced processability characteristics (e.g., like somenonelastomeric polyolefins), and therefore they can be easier to extrudeas thin films. Also, the olefin-based elastomeric polymers tend to bechemically similar to the polyolefins used for nonwovens. This chemicalsimilarity can improve the chemical affinity between the film layer andnonwoven layer(s) in the laminate. Hence, the laminate can have improvedbond strength due to chemical adhesion (e.g., via the chemicalsimilarity) in addition to mechanical bonding.

Optionally, the polyolefin-based layer can include a nonolefin-basedelastomeric polymer, which is blended with the one or more olefin-basedelastomeric polymers and one or more draw down polymers.

A nonolefin-based elastomeric polymer can be, for example, blockcopolymer of vinyl arylene and conjugated diene, natural rubber,polyurethane rubber, polyester rubber, elastomeric polyamide,elastomeric polyether, polyisoprene, polyneoprene, or mixtures thereof.For instance, one group of nonolefin-based elastomeric polymers is theblock copolymers of vinyl arylene and conjugated diene monomers, such asAB, ABA, ABC, or ABCA block copolymers where the A segments comprisearylenes such as polystyrene and the B and C segments comprise dienessuch as butadiene or isoprene. Another group of nonolefin-basedelastomeric polymers is the block copolymers of vinyl arylene andhydrogenated olefin monomers, such as AB, ABA, ABC, or ABCA blockcopolymers where the A segments comprise arylenes such as polystyreneand the B and C segments comprise saturated olefins such as ethylene,propylene, or butylene. A nonolefin-based elastomeric polymer can bestyrene block copolymer (SBC), including but not limited to,styrene-butadiene-styrene block copolymer (SBS),styrene-isoprene-styrene block copolymer (SIS) (e.g., VECTOR 4211provided by Dexco Polymers LP of Houston, Tex.),styrene-isoprene-butadiene-styrene block copolymer,styrene-ethylenebutylene-styrene block copolymer (SEBS),styrene-ethylene-propylene block copolymer (SEP),styrene-ethylene-propylene-styrene block copolymer (SEPS),styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), ormixtures thereof. Some block copolymers include KRATON® Polymersprovided by KRATON Polymers LLC of Houston, Tex. (e.g., Series Dpolymers (such as SIS or SBS copolymers) or Series G (such as SEBS orSEPS block copolymers)), Dexco Polymers LP of Houston, Tex. (e.g., SBSor SIS block copolymers), and Septon Company of America of Pasadena,Tex. (SEP, SEPS, SEBS, or SEEPS block copolymers).

The total amount of the optional nonolefin-based elastomeric polymer canbe, relative to the layer weight, about 1 wt %, about 2 wt %, about 3 wt%, about 5 wt %, about 7 wt %, about 10 wt %, about 20 wt %, about 30 wt%, or about 40 wt %. In some instances, total amount of the optionalnonolefin-based elastomeric polymer can be at least about 1 wt %, atleast about 3 wt %, at least about 5 wt %, at least about 10 wt %, or atleast about 20 wt %. The total amount of the optional nonolefin-basedelastomeric polymer can be no more than about 40 wt %, no more thanabout 30 wt %, or no more than about 20 wt %.

The elastomeric film can optionally comprise other components that, insome instances, modify the film properties, aid in the processing of thefilm, or modify the appearance of the film. Viscosity-reducing polymersand plasticizers can be added as processing aids. High-densitypolyethylene can be added to help prevent age-related degradation of theother polymers. Other additives such as pigments, dyes, antioxidants,antistatic agents, slip agents, foaming agents, heat stabilizers, lightstabilizers, inorganic fillers, organic fillers or combinations thereofcan be added. The amounts of these components relative to the layerweight can be about 0.1 wt %, about 0.5 wt %, about 1 wt %, about 2 wt%, about 5 wt %, about 7 wt %, or about 10 wt %.

Any film-forming process can be used to prepare the elastomeric film.For example, any blending process, such as melt blending, can be used.Also, any extrusion process, such as cast extrusion or blown-filmextrusion can be used to form the film. If the elastomeric film is amultilayer film, the film can be formed by a coextrusion process.

In some applications, the addition of certain components (e.g., the drawdown polymer) to a layer of the elastomeric film confers processingproperties that allow extrusion at line speeds of about 175 fpm (feetper minute), about 200 fpm, about 210 fpm, about 225 fpm, about 250 fpm,about 275 fpm, about 300 fpm, about 325 fpm, about 350 fpm, about 400fpm, about 450 fpm, about 500 fpm, about 750 fpm, about 1000 fpm, about1500 fpm, about 2000 fpm, about 2500 fpm, about 3000 fpm, or about 5000fpm. The extrusion line speed can be, for example, greater than about160 fpm, at least about 175 fpm, at least about 200 fpm, at least about210 fpm, or at least about 300 fpm. The extrusion line speed can be nomore than about 5000 fpm, no more than about 3000 fpm, or nor more thanabout 2000 fpm. In some embodiments, addition of an effective amount ofone or more draw down polymers can provide the aforementioned extrusionline speeds.

The basis weight of the elastomeric film (e.g., a monolayer film) can beno more than about 25 gsm and can be, for example, about 0.1 gsm, about0.25 gsm, about 0.5 gsm, about 0.75 gsm, about 1 gsm, about 2 gsm, about3 gsm, about 4 gsm, about 5 gsm, about 6 gsm, about 7 gsm, about 8 gsm,about 9 gsm, about 10 gsm, about 11 gsm, about 12 gsm, about 13 gsm,about 14 gsm, about 15 gsm, about 16 gsm, about 17 gsm, about 18 gsm,about 19 gsm, about 20 gsm, about 21 gsm, about 22 gsm, about 23 gsm,about 24 gsm, or about 25 gsm. In some instances, the basis weight is atleast about 0.1 gsm, at least about 0.5 gsm, or at least about 1 gsm.The basis weight can be no more than about 25 gsm, no more than about 20gsm, no more than about 15 gsm, or no more than about 10 gsm. In someembodiments, the basis weight of from about 1 gsm to about 10 gsm. Insome embodiments, addition of an effective amount of one or more drawdown polymers can provide the aforementioned basis weights, including,for example, no more than about 25 gsm, no more than about 20 gsm, nomore than about 15 gsm, or no more than about 10 gsm.

The permanent set of the elastomeric film after recovery from beingstretched to 100% of its original length can be no more than about 15%and can be, for example, about 0.5%, about 1%, about 2%, about 3%, about4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about11%, about 12%, about 13%, about 14%, or about 15%. The permanent set ofthe elastomeric film after recovery from being stretched to 100% of itsoriginal length can be at least about 0.5%, at least about 1%, or atleast about 2%. The permanent set of the elastomeric film after recoveryfrom being stretched to 100% of its original length can be no more thanabout 14%, no more than about 10%, or no more than about 7%. In someinstances, the aforementioned permanent set is for films prior toactivation, and in other instances the aforementioned permanent set isfor films after activation. In some embodiments, addition of aneffective amount of elastomeric polymer (i.e., olefin-based elastomericpolymer, nonolefin-based elastomeric polymer, or combinations thereof)can provide the aforementioned permanent set, including, for example, nomore than about 15%, no more than about 10%, or no more than about 7%.

In some embodiments, the elastomeric film layers comprise polymers thatare inherently sticky or tacky. When such elastomeric films are extrudedand wound into a roll, the film can sometimes stick to itself or“block,” sometimes becoming difficult or impossible to unwind. Blockingcan become more pronounced as the film is aged or stored in a warmenvironment, such as inside a storage warehouse. This blocking problemcan be addressed in a number of ways, if desired. For example,antiblocking agents, such as powdered inorganic materials (e.g., silicaor talc) can be incorporated within layers of the film. Antiblockingagents can also be dusted onto the outer surfaces of extruded film asthe film is being formed. The elastomeric film can also besurface-coated with materials that are not sticky, such as a nonblockingpolymer, a brittle nonblocking polymer, a surface coating such as alacquer or ink, or other such coatings.

In a further embodiment of the present invention, the elastomeric filmcan be one or more layers of a multilayer film. In some multilayerembodiments, the elastomeric film includes two or more layers with (1) afirst or polyolefin-based layer which comprises one or more olefin-basedelastomeric polymers blended with one or more draw down polymers, asdiscussed above (e.g., including an optional additional elastomericpolymer that is not an olefin-based elastomeric polymer) and (2) asecond layer that comprises (a) one or more elastomeric polymers blendedwith (b) one or more draw down polymers. The elastomeric polymers in thesecond layer can be can be olefin-based elastomeric polymers, non-olefinbased elastomeric polymers, or combinations thereof. The one or moredraw down polymers of the first layer can be the same or different asthe one or more draw down polymers of the second layer.

In two layer embodiments of the multilayer film, the polyolefin-basedlayer is sometimes referred to as a “skin” layer, a “surface” layer, ora “capping” layer. And the second layer is sometimes referred to as a“core” layer or a “central” layer. The two layer film can be acoextruded multilayer film.

In some embodiments of a three layer film, the film can be a coextrudedmultilayer film with an ABC-type construction. In the ABC-typeconstruction, the A layer and the C layer can be the same or differentcomposition. The A layer and the C layer form the outer layers of thefilm, which are sometimes referred to as the “skin,” “surface,” or“capping” layers. The B layer, that is also referred to as the “core” or“central” layer, is the layer that comprises one or more elastomericpolymers—the elastomeric polymer can be an olefin-based elastomericpolymer, a nonolefin elastomeric polymer, or combinations thereof. Wherethe A layer and the C layer are the same composition, this provides anABA-type construction.

In some instances, the polyolefin-based layer(s) (e.g., the skinlayer(s)) can improve the processability of the elastomeric film, evenwhen the second layer (e.g., the core layer) comprises aless-processable polymer (e.g., a styrene block copolymer). Also,olefin-based elastomeric polymers in the skin layer of the film canprovide a greater affinity for an olefin-based substrate (e.g.,polyolefin fabric) bonded to the surface of the film in a laminate. Thisgreater affinity can improve the overall bond between the film surfaceand the substrate (e.g., fabric fibers).

The one or more elastomeric polymers in the second layer can be the sameas or different from the olefin-based elastomeric polymers of thepolyolefin-based layer, can be the same as or different from theoptional additional elastomeric polymer of the polyolefin-based layer,or can be combinations thereof.

The total amount of the elastomeric polymer in the second layer can be,relative to the layer weight, about 10 wt %, about 20 wt %, about 30 wt%, about 40 wt %, about 50 wt %, about 60 wt %, about 70 wt %, about 80wt %, or about 90 wt %. In some instances, total amount of theelastomeric polymer can be at least about 10 wt %, at least about 20 wt%, at least about 50 wt %, at least about 60 wt %, or at least about 70wt %, least about 80 wt %, or at least about 90 wt %. The total amountof the elastomeric polymer can be no more than about 40 wt %, no morethan about 50 wt %, no more than about 60 wt %, no more than about 70 wt%, no more than about 80 wt %, or no more than about 90 wt %.

The polyolefin-based layer (e.g., as a skin layer) can provide improvedthermal stability and processability when coextruded with another layer(e.g., a core layer comprising SBC's) to form a multilayer. For example,the presence of the polyolefin-based layer can provide extrusion of verythin elastomeric films with little or no draw resonance, basis weightfluctuations, or web instability.

The draw down polymer in the second layer can be chosen from the drawdown polymers as described above and as applied to the polyolefin-basedlayer. The draw down polymer of the second layer can be the same ordifferent from the draw down polymer of the polyolefin-based layer andcan have or confer some or all of the same advantages as the draw downpolymer of the polyolefin-based layer. The identity and amount of drawdown polymer in the second layer can depend on the other components inthe second layer (e.g., the identity of the polymer(s) in the secondlayer), other components/layers of the film or, if applicable,components of the laminate that comprises the film. The total amount ofdraw down polymer (i.e., the combined amount of the one or more drawdown polymer(s)) in the second layer can be about 5%, about 10 wt %,about 15 wt %, about 20 wt %, about 25 wt %, about 30 wt %, about 35 wt%, or about 45 wt %. The wt % is relative to the layer weight of thesecond layer (i.e., total weight of draw down polymer(s) divided by thetotal weight of the layer). In some instances the total amount of thedraw down polymer in the second layer is at least about 5 wt %, at leastabout 10 wt %, or at least about 15 wt %. The total amount of draw downpolymer in the second layer can be no more than about 20 wt %, no morethan about 30 wt %, no more than about 35 wt %, or no more than about 45wt %.

The multilayer elastomeric film can have a basis weight of no more thanabout 40 gsm and can be, for example, about 0.1 gsm, about 0.25 gsm,about 0.5 gsm, about 0.75 gsm, about 1 gsm, about 2 gsm, about 3 gsm,about 4 gsm, about 5 gsm, about 6 gsm, about 7 gsm, about 8 gsm, about 9gsm, about 10 gsm, about 11 gsm, about 12 gsm, about 13 gsm, about 14gsm, about 15 gsm, about 16 gsm, about 17 gsm, about 18 gsm, about 19gsm, about 20 gsm, about 21 gsm, about 22 gsm, about 23 gsm, about 24gsm, about 25 gsm, about 30 gsm, about 35 gsm, about 36 gsm, about 37gsm, about 38 gsm, about 39 gsm, or about 40 gsm. In some instances, thebasis weight is at least about 0.1 gsm, at least about 0.5 gsm, at leastabout 1 gsm, or at least about 2 gsm. The basis weight can be no morethan about 39 gsm, no more than about 35 gsm, no more than about 30 gsm,or no more than about 25 gsm. In some embodiments, addition of aneffective amount of one or more draw down polymers to one or more layerscan provide the aforementioned basis weights, including, for example, nomore than about 40 gsm, no more than about 35 gsm, no more than about 30gsm, or no more than about 25 gsm.

The permanent set of the multilayer elastomeric film after recovery frombeing stretched to 100% of its original length of the multilayerelastomeric film can be no more than about 15% and can be, for example,about 0.5%, about 1%, about 2%, about 3%, about 4%, about 5%, about 6%,about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about13%, about 14%, or about 15%. The permanent set of the multilayerelastomeric film after recovery from being stretched to 100% of itsoriginal length can be at least about 0.5%, at least about 1%, or atleast about 2%. The permanent set of the multilayer elastomeric filmafter recovery from being stretched to 100% of its original length canbe no more than about 14%, no more than about 10%, or no more than about7%. In some instances, the aforementioned permanent set is formultilayer elastomeric films prior to activation, and in other instancesthe aforementioned permanent set is for multilayer elastomeric filmsafter activation. In some embodiments, addition of an effective amountof elastomeric polymer (i.e., olefin-based elastomeric polymer,nonolefin-based elastomeric polymer, or combinations thereof) to one ormore layers can provide the aforementioned permanent set, including, forexample, no more than about 15%, no more than about 10%, or no more thanabout 7%.

The multilayer elastomeric film can, in some embodiments, be made atextrusion line speeds as discussed above for the monolayer elastomericfilm. The compositions of the layers can confer processing propertiesthat allow extrusion at line speeds described herein.

One or more layers of the elastomeric film can optionally comprise othercomponents that, in some instances, modify the film properties, aid inthe processing of the film, or modify the appearance of the film.Viscosity-reducing polymers and plasticizers can be added as processingaids. High-density polyethylene can be added to help prevent age-relateddegradation of the other polymers. Other additives such as pigments,dyes, antioxidants, antistatic agents, slip agents, foaming agents, heatstabilizers, light stabilizers, inorganic fillers, organic fillers orcombinations thereof can be added. The amounts of these componentsrelative to the layer weight can be about 0.1 wt %, about 0.5 wt %,about 1 wt %, about 2 wt %, about 5 wt %, about 7 wt %, or about 10 wt%. These additives can be present in one, several, or all layers of amultilayer elastomeric film.

In some embodiments, as desired, the elastomeric multilayer film caninclude antiblocking agents or other methods/components to addressblocking problems associate with layers having polymers that areinherently sticky or tacky, as discussed in more detail above.

As discussed above, any suitable blending method can be used to blendthe components of the layers together. Also, any extrusion process, suchas cast extrusion or blown-film extrusion can be used to form themultilayer elastomeric film.

By extruding films comprising olefin-based elastomeric polymers or,alternatively, skins comprising olefin-based elastomeric polymers, theprocessability of the elastomeric film can be improved. And the problemssometimes associated with low basis weight films (e.g., fluctuatingbasis weights, draw resonance, web tear-offs, etc.) can be reduced oreliminated. The multilayer films described herein can be easier tomanufacture when the skin layer(s) comprise(s) olefin-based elastomericpolymers, even when there is a high concentration of elastomericpolymers (e.g., SBCs) in the core layer.

FIG. 1 illustrates a schematic of a cast coextrusion film process for anABA-type three layer multilayer film. A polymer composition for theelastomeric film skin layer A is melted in a conventional screw extruder10. Similarly, a polymer composition for the elastomeric film core layerB is melted in a conventional screw extruder 12. The molten polymercompositions are then transferred from the extruders to the feed block16 and the molten polymer layers A and B are then coextruded from theextrusion die 18 to form a molten multilayer polymer web 20. The moltenpolymer web 20 is extruded onto a cast roll 30 where the web is rapidlycooled to form the film 22. The cast roll 30 may be a smooth roll thatmakes a smooth film, or an embossing roll which embosses a pattern ontothe surface of the film. An optional backing roll 32 can assist the castroll 30 in forming the film 22. The film 22 may then pass over optionalequipment such as idler rolls 34 and 36, which facilitate the transferof the film from the cast extrusion section to winder 40 where it iswound and stored to await further processing. This process can bemodified to make an elastomeric film that is a monolayer elastomericfilm.

In some embodiments, the extrusion is performed at line speeds of about175 fpm (feet per minute), about 200 fpm, about 210 fpm, about 225 fpm,about 250 fpm, about 275 fpm, about 300 fpm, about 325 fpm, about 350fpm, about 400 fpm, about 450 fpm, about 500 fpm, about 750 fpm, about1000 fpm, about 1500 fpm, about 2000 fpm, about 2500 fpm, about 3000fpm, or about 5000 fpm. The extrusion line speed can be, for example,greater than about 160 fpm, at least at about 165 fpm, at least about175 fpm, at least about 200 fpm, at least about 210 fpm, or at leastabout 300 fpm. The extrusion line speed can be no more than about 5000fpm, no more than about 3000 fpm, or nor more than about 2000 fpm.

Additional processing steps can be performed on the elastomeric film,such as activating, aperturing, printing, slitting, laminatingadditional layers to the film, and other such processes.

For example, the elastomeric film may be activated by stretching means.Machine-direction orientation (MDO) can be used to activate elastomericfilms in the machine direction, while tentering can activate films inthe cross direction. Incremental stretching rollers can be used toactivate films in the machine direction, cross direction, at an angle,or any combination thereof. In some embodiments, the depth of engagementused for incremental stretching is about 0.05 inches, about 0.10 inches,about 0.15 inches, about 0.20 inches, or about 0.25 inches. The depth ofengagement can be, for example, at least about 0.05 inches or at leastabout 0.10 inches. The depth of engagement can be, for example, no morethan about 0.10 inches, no more than about 0.18 inches, or no more thanabout 0.25 inches.

The elastomeric films described herein can also be used to form alaminate. Such a laminate includes one or more substrate layers and theelastomeric film (e.g., monolayers or multilayers). The substrate layermay be an extensible material including but not limited to anotherpolymer film, fabric, nonwoven fabric, woven fabric, knitted fabric,scrim, or netting. The elastomeric film can be bonded to substratelayers on one or both sides.

When two or more substrate layers are used to make the laminate, thesubstrate layers can be the same or different extensible material. Thecomposition of the substrate layers can be the same or different, evenwhen the same extensible material is used (e.g., two nonwoven layerswhere one nonwoven layer is made from polyolefin and the other nonwovenlayer is made from polyester).

The substrate layer (e.g., nonwoven fabrics) can have a basis weight ofabout 3 gsm, about 4 gsm, about 5 gsm, about 7 gsm, about 9 gsm, about10 gsm, about 15 gsm, about 20 gsm, about 25 gsm, about 30 gsm, about 40gsm, about 50 gsm, about 75 gsm, about 100 gsm, about 150 gsm, or about200 gsm. The basis weight of the substrate layer (e.g., nonwovenfabrics) can be at least about 3 gsm, at least about 5 gsm, or at leastabout 10 gsm. The basis weight of the substrate layer can be no morethan about 10 gsm, no more than about 20 gsm, no more than about 30 gsm,no more than about 50 gsm, no more than about 75 gsm, no more than about100 gsm, or no more than about 200 gsm. If two substrate layers areused, one layer can have a basis weight that is the same or differentfrom the other.

In some embodiments, the substrate layer is a nonwoven fabric. Forexample, the substrate layer can be spunbond nonwoven webs, cardednonwoven webs (e.g., thermally bonded, adhesively bonded, or spunlaced),meltblown nonwoven webs, spunlaced nonwoven webs, spunbond meltblownspunbond nonwoven webs, spunbond meltblown meltblown spunbond nonwovenwebs, unbonded nonwoven webs, electrospun nonwoven webs, flashspunnonwoven webs (e.g., TYVEK™ by DuPont), or combinations thereof. Thesefabrics can comprise fibers of polyolefins such as polypropylene orpolyethylene, polyesters, polyamides, polyurethanes, elastomers, rayon,cellulose, copolymers thereof, or blends thereof or mixtures thereof.The nonwoven fabrics can also comprise fibers that are homogenousstructures or comprise bicomponent structures such as sheath/core,side-by-side, islands-in-the-sea, and other bicomponent configurations.For a detailed description of some nonwovens, see “Nonwoven FabricPrimer and Reference Sampler” by E. A. Vaughn, Association of theNonwoven Fabrics Industry, 3d Edition (1992). Such nonwoven fabrics canhave a basis weight of at least about 3 gsm, at least about 5 gsm, atleast about 10 gsm, no more than about 30 gsm, no more than about 75gsm, no more than about 100 gsm, or no more than about 150 gsm.

The nonwoven fabrics can include fibers or can be made from fibers thathave a cross section perpendicular to the fiber longitudinal axis thatis substantially non-circular. Substantially non-circular means that theratio of the longest axis of the cross section to the shortest axis ofthe cross section is at least about 1.1. The ratio of the longest axisof the cross section to the shortest axis of the cross section can beabout 1.1, about 1.2, about 1.5, about 2.0, about 3.0, about 6.0, about10.0, or about 15.0. In some embodiments, this ratio can be at leastabout 1.2, at least about 1.5, or at least about 2.0. These ratios canbe, for example, no more than about 3.0, no more than about 6.0, no morethan about 10.0, or no more than about 15.0.

The shape of the cross section perpendicular to the fiber longitudinalaxis of the substantially non-circular fibers can be rectangular (e.g.,with rounded corners) which are also referred to as “flat” fibers,trilobal, or oblong (e.g., oval) in the cross section. Thesesubstantially non-circular fibers can provide more surface area to bondto the elastomeric film than nonwoven fabrics with fibers that arecircular in cross section. Such an increase in surface area can increasethe bond strength between the elastomeric film and fibers.

Bond strength between the elastomeric film and the substrate layers ofthe laminate can be measured by any number of methods, including, forexample, ASTM D-1876. In some embodiments, optimum bond strength is abalance between bond strength that is too low (e.g., that can lead todelamination of the film from the substrate) and bond strength that istoo high (e.g., that can lead to inelastic behavior of the laminate,even when activated). Bonding between the layers can be achieved by anymethod, including, but not limited to, adhesive bonding, extrusionlamination, thermal bonding, ultrasonic bonding, calendering, pointbonding, laser bonding, and combinations thereof. The bonding strengthcan depend on the bonding method and variations within a given bondingmethod. For example, for layers bonded by an adhesive, the choice ofadhesive and the amount of adhesive applied to bond the layers can beadjusted to achieve the desired bond strength.

Bonding can also occur between the substrate layer (e.g., nonwoven) andthe elastomeric film during extrusion by heating the film to be molten;this molten film is pressed into the substrate layer to embed thesubstrate into the film to create bonding. In some instances, thisbonding can be enhanced if the chemical composition of the elastomericfilm has a chemical affinity for the chemical composition of thesubstrate layer. Of course, if the elastomeric film is a multilayerfilm, chemical affinity relative to the substrate layer relates to thelayer of the multilayer film that is in contact with the substrate.Similarly, if the substrate is a multilayer substrate or a bicomponentsubstrate, chemical affinity relative to the film relates to thesubstrate component that is in contact with the film.

In some embodiments of the process of making the laminate usingextrusion with heat, the temperature of the extruded molten elastomericweb can be controlled. For example, when the extruded film is of thingauge, the extruded web has less mass to retain heat during theextrusion process. Less mass can result in an extruded molten polymerweb that can solidify rapidly. An extruded polymer film that solidifiestoo rapidly can sometimes result in weaker bond strength because lessembedding of the substrate in the extruded elastomeric film can occur.In some instances, the bond strength is further decreased when theextruded polymer does not have great chemical affinity for the materialsthat comprise the substrate.

In some embodiments, film layers comprising SBC do not have strongnatural chemical affinity for the polyolefinic substrate materials. Tomaintain bonding in these instances, sheets of films comprising SBC andsubstrates with fibers sometimes rely on mechanical bonding forces, suchas those achieved by embedding the substrate fibers into the surface ofthe film. If the film has solidified before contacting the substrate,the fibers cannot be sufficiently embedded into the solidified surfaceof the film. Hence, the bond strength between the film and substrate ofthe laminate can be poor, and the elastomeric material can sometimesdelaminate easily. Bond strength can be enhanced by other bonding means,such as application of an adhesive. In other embodiments, bond strengthcan be enhanced by using a multilayer film that includes one layer witha less compatible polymer (e.g., SBC) and one or more layers with apolymer that is more compatible (e.g., an olefin-based elastomericpolymer).

In other embodiments, laminates having films comprising elastomers thatare chemically similar to the substrate composition can have increasedbonding strength when the substrate is embedded into the film duringextrusion. For example, films comprising polyolefins can have chemicalaffinity for substrates that comprise polyolefins and can therefore haveincreased bonding strength. In some instances, the chemical affinity(e.g., when the film and the substrate comprise polyolefins) can providesubstantial bonding even if there is little or no mechanical bonding(e.g., from embedded fibers in the film). In some instances, if the filmis soft or semi-molten when it contacts the substrate, this can lead toenhanced bonding via mechanical bonding. Of course, other methods ofbonding (e.g., adhesive bonding) can be used to increase bondingstrength.

In some instances, olefin-based elastomeric films do not solidify asrapidly as SBC-based materials. The extruded olefin-based elastomericweb can be semi-molten and soft when it contacts the nonwoven fibers,which allows the fibers to embed into the surface. Hence, olefin-basedelastomeric films, or multilayer elastomeric films with olefin-basedelastomeric skins, can form laminates with stronger bond strength andless tendency to delaminate.

In some instances, the chemical affinity of the elastomeric film may besufficiently high that an acceptable bond strength is obtained, but thelaminate may be difficult to activate due to a number of factors thatmay include, for example, the intimate coupling of the nonwovensubstrate and the film which can hinder the activation process. The highchemical affinity of the elastomeric film for the nonwoven can sometimesresult in roll blocking and thus can sometimes cause problems instoring, transporting, and unwinding of the laminate. Such roll blockingcan be addressed by appropriate measures as described herein or by anyappropriate method.

One method of forming the laminate is adhesive lamination, illustratedin FIG. 2. The elastomeric film 20 is melt-extruded from a film-formingdie 18 and drops to the nip between the illustrated metal roll 30 andbacking roll 32. The metal roll 30 may be chilled to rapidly cool themolten film. The metal roll may also be engraved with an embossingpattern if such a pattern is desired on the resulting film. After theextruded film 22 has cooled and solidified, it passes to an adhesivebonding station, where adhesive 34 is applied by means such as a sprayunit 35 onto the film. Alternatively, the spray unit 35 may sprayadhesive onto the incoming fabric 13. The fabric 13 is unwound from roll11 and introduced into a nip 37 that presses the elastomeric film 22 andthe fabric 13 to bond them together. The laminate 24 may now be woundinto a roll or go on for further processing.

In another embodiment, an extrusion coating process is used to form thelaminate. FIG. 3 illustrates an extrusion coating process. A film 20 ismelt-extruded through a film-forming die 18 and drops to the nip betweenthe illustrated metal roll 30 and backing roll 32. The metal roll may bechilled to rapidly cool the molten polymer film. The metal roll 30 mayalso be engraved with an embossing pattern if such a pattern is desiredon the resulting film. The fabric 13 of the laminate is unwound fromroll 11 and introduced into the nip between the metal and rubber rollsas well. The extruded film 20 and fabric 13 are pressed together at thenip to bond them together. The laminate 24 may now be wound into a rollor go on for further processing.

Additional processing steps such as activating the elastomeric laminate,aperturing the laminate, printing the laminate, slitting the laminate,laminating additional layers to the laminate, and other such processescan be added to the process.

For another example of additional processing, the laminate can beactivated by stretching means. Machine-direction orientation (MDO) canbe used to activate laminate in the machine direction, while tenteringcan activate laminates in the cross direction. Incremental stretchingrollers can be used to activate laminates in the machine direction,cross direction, at an angle, or any combination thereof. In someembodiments, the depth of engagement used for incremental stretching isabout 0.05 inches, about 0.10 inches, about 0.15 inches, about 0.20inches, or about 0.25 inches. The depth of engagement can be, forexample, at least about 0.05 inches or at least about 0.10 inches. Thedepth of engagement can be, for example, no more than about 0.10 inches,no more than about 0.18 inches, or no more than about 0.25 inches.

Laminates of elastomeric films and fabrics are particularly suited toactivation by incremental stretching. As disclosed in thecommonly-assigned U.S. Pat. No. 5,422,172 (“Wu '172”), which isincorporated by reference, laminates of the sort made here can beactivated by incremental stretching using the incremental stretchingrollers described therein.

EXAMPLES

The following examples are presented to illustrate embodiments of thepresent invention. These examples are not intended to limit theinvention in any way.

Example 1

Elastomeric laminates of the present invention were prepared and tested.The laminates comprised a monolayer elastomeric film and two layers ofnonwoven fabric. The monolayer elastomeric films comprised 80%VISTAMAXX™ 6102 polyolefinic elastomer, from ExxonMobil Chemical, 15%ELITE™ 5800 linear low density polyethylene from The Dow ChemicalCompany, and 5% white masterbatch concentrate (Schulman 8500) fromSchulman Corporation. The elastomeric film monolayers were extruded on acast-extrusion line. Films with target basis weights of less than 20gsm, and as low as 14 gsm, were extruded with little or no drawresonance, with no web breakage, and with basis weight fluctuation ofless than 20%. These films were extrusion laminated to two layers of 8gsm spunbond-meltblown-meltblown-spunbond (SMMS) polypropylene nonwovenfabric made by Fibertex Nonwovens A/S of Aalborg, Denmark. The laminateswere then activated by incremental stretching at a depth of engagementof 0.100 inches for the intermeshing rolls. The thin elastomeric filmlaminates showed good stretch and recovery characteristics, and thelaminates were resistant to pinholes and tearing.

Example 2

Elastomeric laminates of the present invention were prepared and tested.The laminates comprised two layers of nonwoven fabric and a multilayerABA elastomeric film, where the ABA layers were about 25%/50%/25% of theoverall multilayer film composition. The A (skin) layers comprised 75%VISTAMAXX™ 6102 polyolefinic elastomer, 15% ELITE™ 5800 linear lowdensity polyethylene, 5% INSPIRE™ D118.01 homopolymer polypropylene fromThe Dow Chemical Company, and 5% ALATHON® m6060 high-densitypolyethylene, from Equistar Chemicals. The B (core) layers comprised 75%VECTOR™ 4211A styrene-isoprene-styrene (SIS) block copolymer (from DexcoPolymer LP of Houston Tex.), 15% ELITE™ 5800 linear low densitypolyethylene, 5% INSPIRE™ D118.01 homopolymer polypropylene, and 5%white masterbatch concentrate (Schulman 8500) from Schulman Corporation.The multilayer elastomeric films were extruded on a cast-extrusion line.Films with target basis weights of less than 20 gsm, and as low as 10gsm, were extruded with little or no draw resonance, with no webbreakage, and with basis weight fluctuation of less than 20%. This filmwas extrusion laminated to two layers of 10 gsm flat-fiber bicomponentPE/PP nonwoven fabric (SPUNBONDED BICO 10 GSM with bilobal ‘Papillon’Filaments) from ALBIS Nonwoven Fabrics of Aschersleben, Germany. Thelaminates were then activated by incremental stretching at a depth ofengagement of 0.100 inches for the intermeshing rolls. The thinelastomeric film laminates showed good stretch and recoverycharacteristics, and the laminates were resistant to pinholes andtearing.

Example 3

Two SMMS nonwoven (spunbond-meltblown-meltblown-spunbond) layers made byFibertex Nonwovens A/S of Aalborg, Denmark with a basis weight of 10 gsmeach were extrusion laminated to a monolayer elastomeric film on bothsurfaces. The elastomeric film comprised 78% VISTAMAXX™ 6102 fromExxon-Mobil Company, 15% linear low density polyethylene (LLDPE) (ELITE5800 from Dow Chemical Company), 5% white master batch (Schulman 8500),and 2% processing aid (LUVOFILM 9679 from Lehmann & Voss & Co. ofHamburg Germany) to make a white elastic film. The film was drawn downto 20 gsm to make the extrusion laminated composite of total basisweight of 40 gsm (i.e., 10 gsm nonwoven+20 gsm film+10 gsm nonwoven).

As a comparison, the same laminate was made except that the film wasmade without adding LLDPE; the film comprised 93% VISTAMAXX™ 6102, 5%white master batch, and 2% processing aid. This film could only drawdown to 46 gsm to make extrusion laminate of total basis weight of 66gsm (i.e., 10 gsm nonwoven+46 gsm film+10 gsm nonwoven). Attempts todraw down this formulation below 46 gsm caused the web to tear.

Example 4

Table 1 shows properties of films made from an olefin-based elastomericpolymer, ethylene-octene olefin block copolymer (INFUSE™ 9107), withvarying amounts of a draw down polymer, LLDPE (ELITE™ 5800).

TABLE 1 Sample 4-A Sample 4-B Sample 4-C Formulation INFUSE ™ 9107 92 8277 (%) ELITE ™ 5800 0 10 15 (%) Processing aid 1 1 1 (LUVOFILM 9679) (%)White Master 7 7 7 Batch (Schulman 8500) (%) % % % Basis permanent Basispermanent Basis permanent Line Speed weight set after weight set afterweight set after (fpm) (gsm) 100% strain (gsm) 100% strain (gsm) 100%strain Draw down 110 20 7.3 n.d. n.d. 20 8.4 performance 130 n.d. n.d.18  7.4 nd n.d. of the 160 15 8.8 n.d. n.d. 15 8.8 formulations 210 WebWeb Tears 10 10.4 n.d. n.d. and their Tears elasticity 300 Web Web Tearsn.d. n.d.  6 11.4  Tears 350 Web Web Tears  5 11.2 n.d. n.d. Tearsn.d.—not determined

Sample 4-A shows that the web tears off during extrusion when producedat line speeds of 210 fpm and higher. At line speeds of 210 fpm andhigher, samples 4-B and 4-C show that films can be made that aresignificantly thinner and that also provide a percent permanent setbetween 10% and 11.5%.

Example 5

Elastomeric laminates of the present invention were prepared and tested.The laminates comprised one layer of nonwoven fabric and an ABAelastomeric film, where the ABA layers were about 12%/76%/12% of theoverall film composition. The A (skin) layers comprised 84% INFUSE™ 9107polyolefinic elastomer, 15% ELITE™ 5800 linear low density polyethylene,and 1% processing aid (LUVOFILM 9679 from Lehmann & Voss & Co. ofHamburg Germany). The B (core) layers comprised 100% VISTAMAXX™ 6102.The elastomeric films were extruded on a cast-extrusion line. The filmshad basis weights of 25 gsm. This film was extrusion laminated to onelayer of 18 gsm (70/30 core/sheath) bicomponent spunbond, produced atFiberweb (Washougal, Wash.). Laminates were activated by incrementalstretching with CD activation at a depth of engagement of 0.140 inchesor 0.160 inches. No pinholes were observed with any of the laminates.

Example 6

Elastomeric laminates of the present invention were prepared and tested.The laminates comprised one layer of nonwoven fabric and an ABAelastomeric film, where the ABA layers were about 12%/76%/12% of theoverall film composition. The A (skin) layers comprised 69% INFUSE™ 9107polyolefinic elastomer, 30% ELITE™ 5800 linear low density polyethylene,and 1% processing aid (LUVOFILM 9679 from Lehmann & Voss & Co. ofHamburg Germany). The B (core) layers comprised 100% VISTAMAXX™ 6102.The elastomeric films were extruded on a cast-extrusion line. The filmshad basis weights of 25 gsm. This film was extrusion laminated to onelayer of 18 gsm (70/30 core/sheath) bicomponent spunbond, produced atFiberweb (Washougal, Wash.). Laminates were activated by incrementalstretching with CD activation at a depth of engagement of 0.140 inchesor 0.160 inches. No pinholes were observed with any of the laminates.

Example 7

Elastomeric laminates revealed the use of the skin layers as tie layersto achieve good bond strength for a variety of nonwovens with flat fiberwebs, round fiber webs, BICO fibers with mixed PE and PP, or sheath/coreof PE/PP. In some instances, the skin layer of the elastomeric film wasethylene-propylene elastomer rich with polypropylene. In some instances,the skin layer of the film included an elastomeric polymer thatcomprised hard and soft segments of ethylene block polymer. The datashowed that using films with skin (e.g., tie) layers of ethylene blockpolymer in contact with ethylene nonwoven or bico nonwoven can enhancethe bond strength. The data also showed that using films with skin(e.g., tie) layers with propylene-rich ethylene-propylene elastomer canbond better to polypropylene nonwovens.

As discussed above in more detail, embodiments of the present inventioninclude elastomeric films with a low basis weight and methods for makingthe elastomeric films. In some embodiments, the elastomeric film is amonolayer film of a polyolefin-based layer. The elastomeric film canalso be a multilayer film having a polyolefin-based layer. Theelastomeric film can also be part of a laminate formed with one or moresubstrates, such as nonwoven fabrics. The choice of components (e.g.,draw down polymers, olefin-based elastomeric polymers, and otherelastomeric polymers) and component amounts in the layers of theelastomeric film can confer both beneficial film properties and filmprocessing properties. For example, elastomeric films (i.e., monolayerand multilayer) that have a low basis weight and good permanent set canbe produced with at high line speeds.

What is claimed is:
 1. An elastomeric film comprising: (i) at least onenon-styrenic elastomeric polymer selected from the group consisting ofcopolymers of polypropylene and polyethylene and mixtures thereof in anamount of at least about 50% of said film; and (ii) at least one drawdown polymer present in a combined amount of about from 5 wt percent toabout 25 wt percent of said layer, said at least one draw down polymeris selected from the group consisting of linear low densitypolyethylene, high density polyethylene, homopolymer polypropylene, andmixtures thereof, wherein said elastomeric film has a basis weight of nomore than about 25 gsm and a permanent set of no more than about 14percent after recovery from being initially stretched to twice itsoriginal size.
 2. The elastomeric film of claim 1, wherein saidcopolymers of polypropylene and polyethylene are present in a combinedamount of from about 50 wt percent to about 90 wt percent of said film.3. The elastomeric film of claim 1, further comprising a nonolefin-basedelastomeric polymer.
 4. The elastomeric film of claim 1, wherein saidcopolymers of polypropylene and polyethylene are present in a combinedamount of from about 70 wt percent to about 90 wt percent of said film.5. The elastomeric film of claim 1, wherein one or more of said at leastone draw down polymer is prepared using a single-site catalyst.
 6. Theelastomeric film of claim 1, wherein said elastomeric film furthercomprises at least one additional layer comprising at least oneelastomeric polymer.
 7. A multilayer elastomeric film with two or morelayers comprising: (1) a first layer comprising, (a) at least onenon-styrenic elastomeric polymer selected from the group consisting ofcopolymers of polypropylene and polyethylene and mixtures thereof in anamount of at least about 50% of said film; and (b) a first draw downpolymer present in an amount of from about 5 wt percent to about 25 wtpercent of said first layer, said first draw down polymer selected fromthe group consisting of linear low density polyethylene, high densitypolyethylene, homopolymer polypropylene, and mixtures thereof, (2) asecond layer comprising (a) at least one elastomeric polymer and (b) asecond draw down polymer, wherein said multilayer elastomeric film has abasis weight of no more than about 40 gsm, and a permanent set of nomore than about 14 percent after recovery from being initially stretchedto twice its original size.
 8. The multilayer elastomeric film of claim7, wherein said multilayer elastomeric film has a basis of weight of nomore than about 25 gsm.
 9. The multilayer elastomeric film of claim 7,wherein one or more of said at least one first draw down polymer isprepared using a single-site catalyst.
 10. The multilayer elastomericfilm of claim 7, wherein said at least one elastomeric polymer of saidsecond layer is a nonolefin-based elastomeric polymer.
 11. Themultilayer elastomeric film of claim 7, wherein said at least oneelastomeric polymer of said second layer is selected from the groupconsisting of block copolymer of vinyl arylene and conjugated diene,natural rubber, polyester rubber, elastomeric polyamide, elastomericpolyether, polyisoprene, polyneoprene, and mixtures thereof.
 12. Themultilayer elastomeric film of claim 7, wherein said at least oneelastomeric polymer of said second layer is a styrene block copolymer.13. The multilayer elastomeric film of claim 7, wherein said at leastone elastomeric polymer of said second layer is selected from the groupconsisting of styrene-butadiene-styrene block copolymer,styrene-isoprene-styrene block copolymer,styrene-isoprene-butadiene-styrene block copolymer,styrene-ethylenebutylene-styrene block copolymer,styrene-ethylene-propylene block copolymer,styrene-ethylene-propylene-styrene block copolymer,styrene-ethylene-ethylene-propylene-styrene block copolymer, andmixtures thereof and wherein said at least one second draw down polymeris selected from the group consisting of polystyrene, high impactpolystyrene, linear low density polyethylene, high density polyethylene,homopolymer polypropylene, and mixtures thereof.
 14. The multilayerelastomeric film of claim 7, wherein said first layer comprises fromabout 10 wt percent to about 90 wt percent of said multilayerelastomeric film and said second layer comprises from about 10 wtpercent to about 90 wt percent of said multilayer elastomeric film.